Descriptions

The warm pool region of the western tropical Pacific is of particular interest to
atmospheric dynamics because it represents a significant source of energy to the
atmosphere. A better understanding of heat transfer driven by mesoscale and
turbulent circulations within this region could lead to improved global circulation
models, and therefore to improved prediction of global weather patterns. A first step
to this understanding is to evaluate empirical data as well as the methods used to
estimate heat transfer, or heat flux, at the surface. Of specific interest here are latent
heat flux, the heat transfer associated with evaporation, and sensible heat flux, the heat
transfer associated with convection and conduction. In this paper, two different
methods of turbulent flux calculation, eddy correlation and the bulk aerodynamic
method are compared. Eddy correlation directly uses turbulence measurements to
estimate heat flux whereas the bulk aerodynamic method relies on similarity theory to
relate heat flux to mean flow quantities. A brief discussion of selection of averaging
length based on flight altitude is included, as well as a comparison of errors introduced
in averaging velocity as a scalar or as a vector. Errors introduced by averaging,
including mesoscale flux enhancement, are evaluated for strong and weak wind cases
during relatively light convection in the region. Finally, month to month variability in
heat flux is evaluated in an effort to further understand the accuracy of various
approximations used in flux calculation.